Rock crushers, such as, conical or gyratory crushers, include assemblies which gyrate or otherwise move to crush material. The assemblies are often moved by an eccentric mechanism, which can be driven by various power sources. A conical or gyratory crusher typically includes a frame having a central hub surrounded by an annular shell. An annular ring is mounted on the annular shell and is capable of vertical movement with respect to the shell. A bowl, which can be provided with a liner, is mounted on the annular ring.
A conical head assembly, which is often provided with a liner, or a mantle, is supported by a bearing mechanism on a stationary shaft supported by the central hub. The eccentric mechanism, mounted for rotation about the stationary shaft, provides gyrational movement of the conical head assembly relative to the bowl. By adjusting the vertical height of the bowl with respect to the conical head, a crushing cavity (gap or space) between the bowl liner (or bowl) and the mantle (or head) can be adjusted to determine the particle size to which the material will be is crushed.
Conventional crushers can be susceptible to unsafe operation and excessive wear if the mantle or head is improperly allowed to spin with respect to the bowl or bowl liner. For example, if a conical or gyratory crusher is operated without any material in the crushing cavity (such as, at start-up and shut-down), the rotational motion of the eccentric mechanism can cause the crushing head to turn with respect to the bowl. When rocks enter the cavity, while the head is improperly spinning, some rocks may eject upward from the crusher. Also, due to the high relative motion between the spinning head and the rock in the cavity, there will be excessive wear on the mantle and liner (e.g., the liners), leading to more frequent changes of the liners and reducing overall productivity of the crusher. The spinning action can cause the mantle and bowl liner or head and bowl to wear excessively, thereby reducing the operating life of such components and increasing the amount of maintenance required for the crusher. The spinning action can also create undesirable high stresses in conical or gyratory crushers.
Heretofore, some rock crushers have included a clutch-based anti-spin mechanism to prevent undesirable spinning action during no-load or underload conditions. With reference to FIG. 1, an exemplary conventional crushing system 10 is shown as an Omnicone.RTM. crusher, manufactured by Nordberg, Inc. Crusher 10 includes a mantle 12 sitting on a crusher head 11. Crusher head 11 gyrates within main frame 15 to crush rock or other material in crushing area or gap 18 between mantle 12 and a bowl liner 16. Bowl liner 16 is mounted on a bowl 13 that is coupled to an annular ring 14. Annular ring 14 sits upon main frame 15.
System 10 includes a clutch-based, friction-based anti-spin mechanism 20 that is discussed in more detail with reference to FIG. 2. Clutch-based, anti-spin mechanism 20 includes a feed plate 22, a locking nut 24, a locking bar 25, a coupling slider 26, a guide guard 27, a coupling adaptor 28, and a back-stop clutch 30. Mechanism 20 is a relatively complex device which operates to prevent head 11 from spinning with respect to bowl 13 (FIG. 1) when system 10 is in an underload or no-load condition.
Mechanism 20 (FIG. 1) is attached to a top portion of head 11 (e.g., underneath the locking bolt which holds mantle 12 to crushing head 11). The placement of anti-spin mechanism 20 at the top of crushing head 11 (near the top of crushing gap 18) constrains the opening of the crusher. For example, the anti-spin mechanism in Omnicone.RTM. crushers, manufactured by Nordberg, Inc., is located at a pivot point of the head motion, which can impinge the available feed-opening sizes and decrease the mobility of large pieces of material (e.g., such as rock), in the crushing cavity. Because of these limitations, some crushers, such as, HP.RTM. crushers, manufactured by Nordberg, Inc., do not utilize an anti-spin mechanism. Clutch-based mechanisms must have a pivot point below the top end of the crusher head, which constrains material flow or movement at that location. Additionally, conventional anti-spin mechanisms can be expensive, fail quite often, and can be difficult to service. In fact, some anti-spin mechanisms are replaced rarely due to the described maintenance problems.
Thus, there is a need for a less expensive anti-spin mechanism that can be utilized with a variety of rock crushers. Further still, there is a need for an anti-spin mechanism that does not decrease the mobility of large pieces of rock at the top end of the crushing cavity and does not impinge upon the feed openings.